Study of structural changes in copper coating on the surface of structural steels working under repeated loads

This article discusses one of the important tasks of studying structural changes in copper coating on the surface of high-quality structural steels. Growing demands for increasing the efficiency of using structural materials and improving their performance properties, as well as more severe operating conditions of oilfield machinery and equipment, require the development of new calculation methods based on effective experimental methods for studying the stress state. One of such effective methods of studying the stress state is the method of galvanic copper plating, which allows determining the stress of parts in real conditions of their processing. The article, based on metallographic and electron microscopic studies, examines the mechanism of growth of copper-plated grains under the action of multiple alternating loads. It has been established that as a result of the complex effect of stresses, volumetric stress states arise. As a result of multiple alternating loading of a steel sample, significant changes occur in the structure of the copper coating on the surface, which are controlled by the appearance of black and colored spots. It has been established that oxidations formed on the copper surface occur not under the influence of atmospheric air, but as a result of internal changes in the electrolytic copper layer under the influence of alternating loads. Grain growth on the copper coating under the influence of alternating loads to which the part is subjected begins at the interface between the copper coating and the base metal.